Video signal generator

ABSTRACT

A video signal generator, employing a multi-output amplifier and a video signal connector, is physically connected to a device under test to eliminate the use of signal cables, to solve the impedance matching issue, and to reduce noise from the signal cables&#39; exposure to high temperatures. Moreover, the video signal generator employs a video algorithm stored in a programmable microprocessor and instructions downloaded to provide on-line adjustable video patterns sets for test. The video signal generator includes the programmable microprocessor, a television encoder, a multi-output amplifier, and a video signal connector.

RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

The present invention relates to a video signal generator, and moreparticularly, to a video signal generator with adjustable videopatterns, which is especially suitable for the video signal test ofdigital video recorders (DVRs) in mass production.

BACKGROUND OF THE INVENTION

In mass production of DVRs, how to economically and rapidly providedifferent video signals to each DVR for burn-in becomes an importanttopic at the test stage. The burn-in for the DVR means the video signalswith different compression ratios are fed, e.g., in a high-temperatureenvironment, into the DVR to increase the load of the DVR during thetest stage. The burn-in confirms the DVR can operate stably in suchhigh-temperature environments. The high-temperature environment iscreated, in general, in an oven with the temperature ranging from 40° C.to 50° C. In addition, the conditions of the burn-in change depending oncustomers' requests; for example, whether the DVR can endure acontinuous seven-day-long burn-in at 50° C., or increasing theenvironmental temperature gradually (generally performed in atemperature-controlled oven) until the DVR shuts down. Also, the numberof video signal input channels may vary, and four, eight, or sixteenvideo signal input channels are commonly used.

FIG. 1 shows a conventional video signal system configured with sixteenvideo signal input channels, which comprises five amplifiers (one is afirst amplifier 11 and the other four are second amplifiers 13), andtwenty-one signal cables C₁-C₂₁. Each amplifier (11 or 13) has one inputport and four output ports. First, a video signal VA1 (obtained by avideo capture equipment such as a video recorder, or a monitor) istransmitted through a signal cable C₁ to the first amplifier 11. Then,the video signal VA₁ is divided into four video signals VA₁₋₁-VA₁₋₄. Thefour video signals VA₁₋₁-VA₁₋₄ are transmitted through four signalcables C₂-C₅ to the four second amplifiers 13 as input signals,respectively. Next, sixteen video signals VA₂₋₁-VA₂₋₁₆ from the foursecond amplifiers 13 are transmitted through sixteen signal cablesC₆-C₂₁ to a device under test (e.g., DVR). If the DVR under test hassixteen video signal input channels, the video signals provided by thevideo signal system of FIG. 1 can only meet one DVR's requirement. Iften DVRs need to be tested at the same time, the layout of the signalcables will be complicated and chaotic (at least 210 signal cables and40 amplifiers required).

Therefore, the conventional video signal system of FIG. 1, used at thetest stage in mass production, will result in the problems as follows.First, when numerous DVRs under test need to be tested simultaneously,incorrect wiring of the numerous signal cables occurs easily. Second,much human effort is needed to correctly connect the signal cables tothe corresponding DVR under test. Third, the layout of the signal cablesin FIG. 1 is prone to cause an impedance matching issue and thus,distorted video signals. Fourth, when numerous DVRs under test need tobe tested simultaneously, they are placed in a largetemperature-controlled room. In general, the manufacturers of DVRs rentthe large temperature-controlled room from an external researchinstitute; for example, a certified laboratory in the IndustrialTechnology Research Institute of Taiwan. In the rented room, complicatedand messy signal cables are absolutely not allowed. Fifth, the videosignals in the signal cables are affected by high temperature (aboutfrom 40° C. to 50° C.) during burn-in, and accordingly, the test resultis affected. Sixth, to meet different customers' requirements, differentvideo patterns have to be available. Even for a single customer, videopatterns with various complex degrees are required to perform theburn-in process; for example, video patterns with various compressionratios. If the conventional video signal system of FIG. 1 is used, thesource (e.g., a monitor) of the video signal VA₁ has to change and thus,it is very inconvenient to perform the burn-in process in such a largetemperature-controlled room.

To solve the above problems, it is necessary to develop a video signalgenerator providing adjustable video patterns to rapidly andeconomically perform video signal testing of DVRs.

BRIEF SUMMARY OF THE INVENTION

A objective of the present invention is to provide a video signalgenerator, which employs a multi-output amplifier and a video signalconnector. The video signal generator is detachable and physicallyconnected to a device under test to eliminate the use of signal cables,to solve the impedance matching issue, and to reduce the noises fromsignal cables exposed to high temperature.

Another objective of the present invention is to provide a video signalgenerator using a video algorithm stored in a programmablemicroprocessor to provide on-line adjustable video pattern sets fortesting.

In order to achieve the objectives, the present invention discloses avideo signal generator comprising a programmable microprocessor, atelevision (TV) encoder, a multi-output amplifier and a video signalconnector. The programmable microprocessor is used to store the videoalgorithm that generates a first digital video signal, where theprogrammable microprocessor comprises a memory to store plural programcodes (e.g., algorithms). The TV encoder is used to transform the firstdigital video signal to a first analog video signal. The multi-outputamplifier is used to transform the first analog video signal to pluralsecond analog video signals. The video signal connector detachably andphysically connects to a device under test, and transmits the secondanalog video signals to the device under test.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will be described according to the appended drawings.

FIG. 1 shows a schematic view of a conventional video signal systemconfigured with sixteen video signal input channels.

FIG. 2 is a schematic view of the functional block of the firstembodiment of the video signal generator of the present invention.

FIG. 3 is a schematic view of the functional block of the secondembodiment of the video signal generator of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 is the functional block of the first embodiment of the videosignal generator 2 of the present invention. The video signal generator2 comprises a programmable microprocessor 21, a TV encoder 22, amulti-output amplifier 23, a download port 211 (a USB port is used inthe current embodiment), a pattern switch 222 (a DIP switch is used inthe current embodiment), and a video signal connector 24. Theprogrammable microprocessor 21 is used to store a video algorithm thatcan generate a first digital video signal DVS . The programmablemicroprocessor 21 is selected from the group consisting of a single-chipmicroprocessor (e.g., an 8051 microcontroller), a digital signalprocessor chip, or an FPGA (field programmable gate array). The videoalgorithm can be modified using instructions Ins downloaded through thedownload port 211 and therefore, the video patterns associated with thefirst digital video signal DVS₁ are modified, wherein the download port211 is electrically connected to the programmable microprocessor 21. Theprogrammable microprocessor 21 also preloads plural video pattern setsthrough the download port 211, and the pattern switch 222 selects one ofthe video pattern sets, which is directly sent to the TV encoder 22without the processing of the video algorithm. Thus, adjustable videopattern sets are available on line for testing. The video pattern setscomprise RBG video patterns, random video patterns and color bar videopatterns. The TV encoder 22 transforms the first digital video signalDVS₁ to a first analog video signal AVS₁. Then, the multi-outputamplifier 23 transforms the first analog video signal AVS₁ to pluralsecond analog video signals AVS₂. Afterwards, a video signal connector24 with plural pins (e.g., a standard D-15 VGA Male connector) is usedto transmit the second analog video signal AVS2 to a device under test(not shown). The video signal connector 24 is physically connected tothe device under test and the video signal connector 24 is detachablefrom the device under test.

In the current embodiment, the device under test has eight video signalinput channels. That is, the video signal generator 2 uses the videosignal connector 24 to physically connect to the corresponding videosignal input connector (e.g., a standard D-15 VGA Female connector)without the signal cables. Thus, noises due to signal cables beingexposed to high temperature are reduced. Meanwhile, since the videosignal generator 2 is physically connected to the device under test,both carried on the conveyer and moving together; that is, the videosignal generator 2 of the present invention is portable.

FIG. 3 is the functional block of the second embodiment of the videosignal generator 2′ of the present invention. The video signal generator2 comprises a programmable microprocessor 21, a TV encoder 22, amulti-output amplifier 23, a download port 211 (a USB port is used inthe current embodiment), a pattern switch 222 (a DIP switch is used inthe current embodiment), a video signal connector 24, a temperaturesensor TT, a wireless receiver 26, an input switch 25 and an analogvideo signal input port 27 (a BNC (Bayonet Nut Coupling) connector isused in the current embodiment). To monitor the environmentaltemperature during burn-in, the temperature sensor TT senses atemperature signal Temp and sends it to the programmable microprocessor21, then the programmable microprocessor 21 transforms the temperaturesignal Temp to digital form and adds the digital form thereof to thefirst digital video signal DVS₁. Thus, the temperature information canbe displayed on a monitor (not shown) and connected to the device undertest, for technician's reference.

Sometimes, the client requests the ability to check the video quality,which is shown by the device under test, resulting not only from thepreloaded video pattern sets, but also from the video signals captureddirectly from outside. Consequently, the analog video signal input port27 is used to receive a third analog video signal AVS₃ providedexternally, which is then sent to the input switch 25. The input switch25 is connected between the TV encoder 22 and the multi-output amplifier23. Either the first analog video signal AVS₁ or the third analog videosignal AVS₃, which is selected by the input switch 25, is sent to themulti-output amplifier 23. To analyze the testing result of the deviceunder test, some key parameters, such as the current system temperature,the system compression ratio, the elapsed time after burn-in . . . etc.,are recorded. Therefore, the status of the shutdown device is known fromthe video patterns associated with the key parameters. To provide asimple and convenient video signal source, the wireless receiver 26 isused to receive a second digital video signal DVS₂.

After being processed by the programmable microprocessor 21, the seconddigital video signal DVS₂ is then sent to the TV encoder 22. Thewireless receiver 26 is in compliance with the Wi-Fi protocol, theBluetooth protocol, or the GSM (global system for mobile communication)protocol. In other embodiments, the analog video signal input port 27 isan RCA type connector or an F type connector.

In the third embodiment, the temperature sensor TT of FIG. 3 is replacedwith an external expansion circuit capable of connecting a thermometer,a hygrometer, or an accelerometer to sense an environment signal (i.e.,a temperature signal, a humidity signal, or a vibration signal). Theenvironment signal is sent to the programmable microprocessor as a keyparameter.

Without external signal cables connected between the device under testand the multi-output amplifier, the video signal generator of thepresent invention can operate in a large temperature-controlled room(from approximately 40° C. to 65° C.) and eliminate distorted videosignals due to exposure of the signal cables to high temperature as inthe prior art. The video signal generator of the present inventionemploys a video signal connector detachably and physically connected toa device under test. Thus, no complicated signal cables are required andthe impedance matching issue is resolved. Additionally, a videoalgorithm, stored in a programmable microprocessor, provides on-lineadjustable video pattern sets for testing. According to the abovedescription, the video signal generator of the present invention couldachieve the expected objectives.

The above-described embodiments of the present invention are intended tobe illustrative only. Numerous alternative embodiments may be devised bythose skilled in the art without departing from the scope of thefollowing claims.

1. A video signal generator, comprising: a programmable microprocessorstoring a video algorithm for generating a first digital video signal; atelevision encoder transforming said first digital video signal to afirst analog video signal; a multi-output amplifier transforming saidfirst analog video signal to a plurality of second analog video signals;and a video signal connector being physically connected to a deviceunder test, and transmitting the second analog video signals to saiddevice under test.
 2. The video signal generator of claim 1, furthercomprising: a download port connected to said programmablemicroprocessor to download instructions to modify said video algorithm.3. The video signal generator of claim 1, further comprising: an analogvideo signal input port and an input switch to receive a third analogvideo signal provided externally.
 4. The video signal generator of claim3, wherein said input switch is connected between said televisionencoder and said multi-output amplifier, said analog video signal inputport being connected to said input switch.
 5. The video signal generatorof claim 1, further comprising: a wireless receiver receiving a seconddigital video signal and transmitting said second digital video signalto said programmable microprocessor.
 6. The video signal generator ofclaim 5, wherein the wireless receiver is in compliance with Wi-Fiprotocol.
 7. The video signal generator of claim 1, further comprising:an external expansion circuit transmitting an environment signal to saidprogrammable microprocessor.
 8. The video signal generator of claim 7,wherein the environment signal is a temperature signal.
 9. The videosignal generator of claim 7, wherein the environment signal is avibration signal or a humidity signal.
 10. The video signal generator ofclaim 1, being operable below 65° C.
 11. The video signal generator ofclaim 1, wherein said programmable microprocessor preloads a pluralityof video pattern sets.
 12. The video signal generator of claim 11,further comprising: a pattern switch selecting and sending one of thevideo pattern sets to said television encoder.
 13. The video signalgenerator of claim 1, further comprising: a download port connected tosaid programmable microprocessor so as to preload the video patternsets.
 14. The video signal generator of claim 11, wherein the videopattern sets comprise RGB video patterns, random video patterns, andcolor bar video patterns.
 15. The video signal generator of claim 1,wherein the programmable microprocessor is a field programmable gatearray.
 16. The video signal generator of claim 1, wherein theprogrammable microprocessor is a single-chip microprocessor.
 17. Thevideo signal generator of claim 5, wherein the wireless receiver is incompliance with Bluetooth protocol.
 18. The video signal generator ofclaim 5, wherein the wireless receiver is in compliance with GSMprotocol.